The elastic wave reflection method is one of the effective methods of detecting the thickness of the top coal seam.

声波反射法是目前顶煤厚度探测的有效方法之一。

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The elastic wave reflection method is one of the effective methods of detecting the thickness of the top coal seam.

声波反射法是目前顶煤厚度探测的有效方法之一。

youdao